The 'A' flag, or Alpha flag, is used to represent the alphabetic character 'A' for use in a message between boats. It also means "I have a diver down; keep well clear at slow speed."
From the International Code of Signals, this long-lasting nautical flag is made from nylon fabric with double-stitched seams, canvas heading and grommets. Made to order. Allow 2 weeks for delivery.